9.1.4 @key{key-name}

Use the @key command for the conventional name for a key on a
keyboard, as in:

@key{RET}

You can use the @key command within the argument of an
@kbd command when the sequence of characters to be typed
includes one or more keys that are described by name.

For example, to produce C-x ESC and M-TAB you
would type:

@kbd{C-x @key{ESC}}
@kbd{M-@key{TAB}}

Here is a list of the recommended names for keys:

SPC

Space

RET

Return

LFD

Linefeed (however, since most keyboards nowadays do not have a Linefeed key,
it might be better to call this character C-j)

TAB

Tab

BS

Backspace

ESC

Escape

DELETE

Delete

SHIFT

Shift

CTRL

Control

META

Meta

There are subtleties to handling words like ‘meta’ or ‘ctrl’ that are
names of modifier keys. When mentioning a character in which the
modifier key is used, such as Meta-a, use the @kbd command
alone; do not use the @key command; but when you are referring
to the modifier key in isolation, use the @key command. For
example, write ‘@kbd{Meta-a}’ to produce Meta-a and
‘@key{META}’ to produce META.

As a convention in GNU manuals, @key should not be used in
index entries.